While I do think a horn is a good device for a car to have, I wish it were directional and could be aimed. I don't think a honk is necessary when passing cyclists. Most cyclists can hear/see a car approaching. On the flipside, if a cyclist is so much in the zone (zoned-out) and tuned out of the rest of their environment/surroundings then maybe they ought not to be riding the public roads because they've become a safety hazard to themselves as well as others.